The effect of Diabetes on the eye is called Diabetic Retinopathy. A large percentage of patients with uncontrolled diabetes will develop diabetic retinopathy and the chances of developing eye problems increase the longer a patient has diabetes. The severity of diabetic retinopathy is often linked to high and inconsistent blood sugar levels. It is important to have regular hemoglobin A1C blood tests with a primary care physician or endocrinologist, as well as monitoring blood sugar levels and blood pressure. Diabetic retinopathy is divided into two phases: nonproliferative diabetic retinopathy and proliferative diabetic retinopathy.
There are two types of Retinopathy.
Nonproliferative Diabetic Retinopathy (NPDR)
In NPDR, blood vessels that have been damaged by diabetes are weak. The weak blood vessels can leak blood or blood products, forming dot-like hemorrhages or retinal edema (swelling). Vision can remain unchanged during the early stages of NPDR, but accumulation of fluid or blood in the retina can cause a decline in vision. NPDR can be further rated on severity from mild, moderate, or severe.
Proliferative Diabetic Retinopathy (PDR)
In PDR, further damage to blood vessels leads to oxygen deprivation (ischemia) in the peripheral retina. The body attempts to maintain oxygen delivery to these areas by growing new blood vessels (neovascularization). However, these abnormal blood vessels are fragile and often break, leading to vitreous hemorrhage or bleeding within the eye. This can cause a sudden decrease in vision, often accompanied by spots, floaters, or webs. In later stages of the disease, neovascularization can occur in other areas of the retina (NVE), the optic disk (NVD), or the iris (NVI). NVI can cause high intraocular pressure (neovascular glaucoma), which can lead to permanent vision loss. Scar tissue formation and traction on the retina can cause serious complications including tractional retinal detachments.
Diagnosis and Testing
A dilated examination is necessary to diagnose any signs of diabetic retinopathy. The longer a person has been living with a diagnosis of diabetes, the greater the risk of developing NPDR and PDR. A combination of optical coherence tomography (OCT), fluorescein angiography (FA), and fundus photography help an ophthalmologist diagnose and monitor diabetic retinopathy. If vitreous hemorrhage has occurred, an ultrasound may be performed to scan internal eye structures.
Anti-Vascular Endothelial Growth Factor (VEGF) inhibitors such as Avastin, Eylea, and Lucentis are useful in minimizing or eliminating macular edema caused by diabetic retinopathy. Anti-VEGF inhibitors are injected into the eye during an in-office procedure called an intravitreal injection. The injection is painless and takes a few minutes. Steroids can also be injected into the eye to reduce diabetic macular edema. Often, a combination of injections and laser therapy are used to manage diabetic retinopathy.
Pan-Retinal Photocoagulation (PRP), a laser therapy, has been proven effective in controlling diabetic retinopathy in a majority of patients. PRP is used to treat areas of the retina that are ischemic due to damaged blood vessels and leakage. The goal of PRP is to prevent further vision loss by arresting the progression of the disease. It may take several sessions of PRP to reach the desired effect.
Diabetes is a chronic condition so the effect on the eyes can continue to worsen with time. Additional laser treatments, injections, or retinal surgery could be necessary. A vitrectomy is a common surgery for diabetics. If a vitreous hemorrhage does not clear, a surgical procedure can remove the hemorrhage (blood) and may also relieve tension on the retina that could lead to retinal detachment or tears (link to page).
As with any procedure, there are risks and benefits that will be discussed with your physician prior to treatment.